Fabric moisture absorbency tester



March 13, 1951 s; P, HUNT 2,545,281

FABRIC MOISTURE ABSbRBENCY TESTER ATTORNEYS March 13, '1951 s. P. HUNT FABRIC MOISTURE ABSORBENCY TESTER `4, Sheets-:Sheet 2 Filed OCt. 19, 1948 ATTORNEYS March 13, 1951 s. P. HUNT 2,545,281y

FABRIC MOISTURE ABSORBENCY TESTER' Y Filed Oct. 19, 1948 4 Sheets-Sheet 3 Oy a 79 24 a? /cf f6 o o 25 -\/5 ATTORN EYS March 13, 1951 s. P. HUNT 2,545,281

FABRIC MOISTURE ABSORBENCY TESTER A @gaf ATTORN EYS Patented Mar. 13, 1951 FABRIC MOISTURE ABSORBENCY TESTER Stanley Paul Hunt, Charlottesville, Va., assignor to Institute of Textile Technology, Charlottesville, Va., a corporation of Virginia Application october 19, 1948,'ser'ia1No. 55,383

Y l This invention relates to instruments for determining the liquid absorbency characteristics of specimens f different materials. More particularly, the invention is concerned with a novel instrument for determining the rate, at which aliquid is absorbed by a specimen, and also the rates, atwhich a specimen absorbs liquid during successive stages of absorption. The new instrument is of simple inexpensive construction and it is easy to operate and maintain in working condition. In the use of the instrument, it is not necessary to employ a specimen of specific size and theinstrument may thus be used for determining the absorbency of a finished article without mutilation of the article. The instrument may b-e employed intesting specimens o materials of various kinds and may be advantageously used in the textile industry to determine the rate, at which water is absorbed by fabrics, for example, terry and diaper cloths. A form of the instrument suitable for use in fabric testing will, accordingly, be illustrated and described in detail for purposes of explanation.

The problem of measuring the rate of absorption of water by textile products has had attention over a long period of time and Various tests have been developed for the purpose. When it is desired to determine the rate at which a yarn or fabric will be wet when immersed in a solution in a manufacturing operation, the test employed involves immersing a standard skein of the yarn in water and noting the time required Yfor the replacement of the attached air bubbles by water.v While this testv has been useful in determining the action of wetting agents, it is not satisfactory for evaluating the behavior of fabrics, such as towels, diapers, etc. in taking up moisture from the body. l

A test, that has been developed for vdeterminfabrics, involves allowing the specimen to soak ,up moisture through a porous plate of ceramic material, and then weighing the specimen after various periods of time. Such a test is not satisfactory in that, in the handling of thek specimen to weigh it, unknown amounts of moisture evaporate and this introduces errors. Also, in order to obtain time intervals su'iciently long for convenient handling ofthe sample, the plate must hai/every fine pores,` so that most of the resistance to iiow-of the water occurs in the plate and not in the sample;l This makes the test insensitiveto changes in the properties in the sample in this range and also it is difcult to -obtainv plates,` which? are of uniform resistance l 14 claims. (ci. "r3- mi ing the water absorbency of towels and like ,40

2 and will thus give the same results for a given sample at different times. A further diiculty is that the porosity of a given plate varieslin the course of time because of the clogging of the pores by bers, etc.

The present invention is directed to the prov ision of aninstrument for measuring the ab` sorbency of materials, which overcomes the objections to the prior testing equipment and determines the rate of absorption under conditions approximating those of the use of the article. The new instrument makes possible the determination of the rate, at which a material absorbs liquid during a short period of time, and of the rates of absorption during successive stages. In the instrument, the rate of take-up of the liquid is dependent wholly on the characteristics of the sample and is not affected by extraneous -factors, such as the resistance of a porous plate to the flow of the liquid therethrough. The instrument operates automatically, when the sample is brought into contact with the liquid, to` start a' timing device and to stop the device, when a given quantity of liquid has been taken up. As the liquid is freely supplied to the sample during the determination and the timing is automatic, the results given by the instrument are of a high degree of accuracy.

For a better understanding of the invention,

reference may be had to the accompanying Y drawings, in which Fig. 1 is a view of the new instrument in front elevation; A

Fig. 2 is a plan view of the instrument;

Figs. 3, 4, 5, and 6 are sectional views on the lines 3 3, 4 4, 5 5, and 6 6, respectively, of Fig. 1;

; Fig. 7 is a wiring diagram of one form of the instrument;

Fig. 8v is a graph showing results obtainedin .testing three specimen towels; and

.` Fig. 9 is a diagrammatic view illustrating a modified form of the instrument.

The instrument in the form illustrated comprises a base I0 mounted upon leveling screws I I and carrying a pair of spirit levels I2, I3 disposed at right angles to one another, so that the base can be placed on a supporting surface in exactly horizontal position. At one end, the base ,carries a support I4, on top ofwhich is mounted a vessel I5 for the liquid to be absorbed. The lvessel comprises a base plate I6, on which is mounted 'a section I'I of a hollow cylinder pro- Avidedat its top with a flange I8, on which rests api-lat ring' I9`with a gasket 20 interposed between the ilange and the ring. A screen 2| is mounted in the opening through the flat ring I9 and a top plate 22 of less inner diameter than the diameter of the screen is mounted on top of the ring. The top plate is provided With a peripheral tubular ange 23 and the top plate and the flat ring I9 are secured to-flange I8 by ar plurality of bolts 24, Whichpass. through openingsl in theV The screen 2| used in the instrument iszprefer-v ably Wire cloth of 50 or 60 mesh Woven in a tvvill Weave The individual. Wires are Of. acorrosion. reSStant metal',v such as Monel metal, and about .011 in diameter. The top plate is made of metal and' about .01 in thickness, and the top of the screen is in contact with the bottom of the topl plate. The openingj through the top plate determines the area of the sample, by Which the liquidY is to be taken up, andthe opening may conveniently have an area ofl 25 sq. cm. While awire cloth screen is preferred, the screen may be of plastic materiall havingr openings ne enoughV to transmit the liquid by capillarity to the sample but ofgsufiicient size, so that the resistance to flow ofthe liquid through the screen openings isv negligible.

A pair of plates 26 are mounted onn the support I4-- to the rear of vessel- I5 with their facesparallel. Anarm 211s mounted on ahorizontal pivot pin 28-received inl openings in the-platesandv the arm is free to swingn in a verticale plane, which passes through the centerof the screen. The plates 26z are connected byA a stoppin 30, which is engaged bythe arm 21 and prevents it from passing below the horizontal, when itis swung down from anv upright position. llllhe arm 21 carries-a tubular guide31| at its outer end; in which ismovablymounted a stem 32` carrying` a handle oriknob 34 at-oneendand a perforated pressure plate 35 at theother. end'. The plate 35 has a diameter approximatelyv the sameas: the inner diameter of` the flatfring I9. The. construction is such that, when the arm 21.. is; swung. tohorizont'al` position to come to` rest againstthestop pin 30, the pressure plate 35 is concentric With and a bushing. 42 is adjustablymounted on. theVv road' andV held in.position.by a. set screw 42a. The bushing carries anV arm- 43; whichY encircles the rod and terminatesat itsfree end in a. ring-43a., in which is supported a glassutank 44-1forfthe liquid to be absorbed. Thetank hasY an inlet 45: at its upperend closed by a. stopper and; at its lower end; has a plugvalve 46', fromk which leads.' an outletV tube4 1 The outlet tube is.V connectedby-.a Ieng-thofrubber tubing 48 to one leg off a T 49, the oppositeleg of-*Which is Vconnected by a. length of tubing 58 toA oneleg-ofa T 5|; Another leg off-T isconnected bya length-of tubingl52` to aninletftubef53; which. is inserted in an opening through cylinder.Y Il Thethirdleg of T551; carries 4 a length of tubing 54, which is provided with a shut-off 55.

A pair of end plates 55 are mounted on base I5 at one side of support i4 and are connected by parallel guide rods 51 extending lengthwise of the base. The guide rods pass through openings in a pair of slide plates 58, Which are connecteolV by parallel slide rods 59, to, form a frame. One of the slide plates 53-carries a pointer 90 and the slide plates are connected by a bar 6| carrying a scale. A carriage 62 is mounted to slide on rods 5S, which pass through openings in the carriage. The carriage is provided with a pointer 63 adjustably mounted thereon and vpointing to the scale on bar 6|. A tube base G4 mounted on the carriage carries a socket B5 for a photocell B5 andabracketE51r mounted on base 64 is provided With ay socket for a lamp 68, which lies in front of the photocell and spaced therefrom. The lamp and the photocell are enclosed Within a casing 69.

A capillary tube. 15iis mounted in loopson stems 12|, which are received' in sockets in4 members 12;

,threaded into openings the end platesA 55.

Eachmember` 1,2' hasia thumbscrevv 13. to, engage' its stern` andf hold` it in adjusted vertical, position. The capillary tube extends through casing; 6 9gb e. tvveenlamp 58 and'- photocell S5: andi one end oft the` tubeis connected. by alength of rubber.- tubing 14 to the third' leg or 1:'v 4.91. In the use 0f the instrument, the capillary.`v tube ismounted in horif zontal position, and pointer.- 6.9 terminates close; to the tube.

A housing 15 is mounted on top of base |0 to; the, rear of. the. capillaryl tube structure, Within the housing, is an amplifyingunit, generally designated 1.5. The, instrument; isalso4v provided with an. electricany.A driven timer 1.1;,.which indicates. time, in secondsand ractions thereof., As showninv the. Wiring; dia-gram,V the timer-` is; Connectedacross apower. line; 1.8 and' the: timer circuit in-Y ciudes a. Switch, 139; normally, closed. and capable.. of being; openedgbyl a relay Rpperated by theam.- plied outputl of the; photocell 65, The timer circuit4 also includes theA starting switch 39 operable by arm: 2.1.,

In the use off,-the.iii striiriierity the.; Capillarr tube is initially adjusted t0.. horizon-tal position. with theA loweriedgeofvthe tubepassage inthe level of the-top of the; screenv 2|j. A quantity of liquid to beA absorbed,y such as Water-,ds then permitted to flow.from,tanlt-A 44, until the level4 of the liquid in the vessel, |55is at the top. ofA the level.. of the screen.. and thev endv of. thej liquid. column in-i thetubeisat a:c,onvelnientv point HearY the zeroA end of thescaleon-barfl. The; arm.r 2,1 is raised: to upright-.position andthe lnobf 34Y is pulled out- Wardly to hriilgftheperfoiaied plate 3 5 against the end of guide 3|. The sample is then.V laid to rest onV top of ilanger23, outof contact with the screen,V The slid/.ei Struture-,y comprising slide plates 58, and;K rodsv 579,f is moved on rods. 511 to bring the pointer 60; inexact alignmentwith the end,y of.; the liquid' columnY in thecapillary tube. The. photocellk carriage 6,2 is next; moved along rods 59.;untilA its pointer 53 indicatesr the desired pointy on the scale on. bar 6|. 'Ilhe scale is in terms of milligrams of liquid and pointer 63 indicates .the numberrotmillieramsof liquidv between pointer; 6,6. and theV iihotocell To test the.` absorloencr of; the sample.. the. QD- erator; grasps; theA knob. 34.-V on the stem; carrying.

the perforatedznlate- 3 5; and. Swiiflgsatheiarm`- downy to .they horizontal, simultaneously; pushing: on the stem;l P1ate:.35 thus depresses.- the. unsupported` part.; of; the. sample. vvithin-` flange,l 23.l into. com

tact with the screen and, since the nal movement of the plate and sample is in a vertical direction, the sample makes instantaneous contact with the entire exposed area of the screen. As the arm 21 reaches the horizontal, switch 39V is closed and the timer starts to operate. So long as the beam from lamp 68 passes through liquid in the capillary tube on its way to the target surface of the photocell, no action occurs, but, as the sample takes up liquid, the liquid flows from the capillary tube and, when the end of the liquid column passes through the beam from the lamp, a shadow is cast on the photocell and this results in energization of the relay R, the opening of switch 1S, and the stopping of the timer.

The results obtained with the instrument in testing the absorbency of three different towel samples are represented in the graph of Fig. 8.v Gf these samples, those designated towel #l and towel V#2 were new towels manufactured by-different companies and towel #3 was one, which hasbeen in regular domestic use for a considerable period and laundered several times. Experience with the instrument has shown that the rate of absorbency is linear withrespect to small quantities of water, when the fabric does not approach saturation, and the slope of the curves on the graph is thus the rate ofA absorption. This rate may be expressed in terms of milligrams of water absorbed per square centimeter of exposed fabric per second and, for convenience, is referred to as an absorbency factor. The time required for the fabric to begin to pick up water is a signicant factor in considering the characteristics of a sample and this factor, Awhich may be termed the "induction factor, is the distance from the origin to the intercept of the curve with the time axis. The induction period may be obtained directly from the graph by extrapolation. As shown by the graph, the induction factor was 2.5 seconds for towel #l and 1.65 seconds for towel #2, both of which were new towels. Towel #3, which had been in use and laundered repeatedly, had a zero induction factor. The absorbency factor of the three towels was 10, 28.2, and 35.3, respectively, which indicates that the laundered towel was superior in this respect to either of the two new towels and that towel #2 was superior to towel #1.

The modified form of the instrument shown in Fig. 9 is generally similar to that described, except that it is provided with a plurality of timers 80, all of which are started simultaneously, when the sample is depressed into contact with the screen. Each timer is provided with its own photocell 8l, lamp 82, yand switch controlled by a relay 83, so that, as the end of the water column in the capillary tube 10' passes the successive vof the screen, means for supplying the liquid to the vessel and tube, a timing device, means for pressing the sample upon the screen and simultaneously starting the timing device, andmeans operable, when the end of the liquid column in the tube has passed beyond a selected point, for stopping the timing device.

2. Apparatus for measuring the rate of absorption of a liquid by a sample of material, which comprises a vessel having a top opening, a screen mounted horizontally across the opening, a capillary tube connected at one end to the vessel and mounted horizontally with its passage in the plane of the screen, means for supplying the liquid to the vessel and tube, a timing device, means for pressing the sample upon the screen and simultaneously starting the timing device, means for passing a beam of light through the liquid column in the tube at a selected point, and means responsive to the change in the`beam, when the end of the liquid column has passed beyond the beam, for stopping the timing device.

3. Apparatus for measuring the rate of absorption of a liquid by a sample of material, which comprises a vessel having a top opening, a screen mounted horizontally across the opening, a capillary tube connected at one end to the vessel and mounted horizontally with its passage in the plane of the screen, means for supplying the liquid to the vessel and tube, a timing device, means for pressing the sample upon the screen and simultaneously Astarting the timing device, means for passing a beam of light through the liquid column in the tube at a selected point, a photocell in the path of the beam beyond the tube, and means operating in response to the variation in the output of the photocell caused when the end of the liquid column has passed beyond the beam, to.

stop the timing device.

4. In apparatus for measuring the rate of absorption of a liquid by a sample of material, the combination of a vessel having a top opening, a screen mounted horizontally across the opening, a plurality of spaced. supportingV elements mounted in the walls of the opening and engaging'the screen from beneath, a capillary tube connected at one end to the Vessel and mounted horizontally with its passage in the plane of the screen, means for supplying the liquid to the vessel andY tube', and means for pressing the sample flat upon the screen.

5. In apparatus for measuring the rate of absorption of a liquid by a sample of material, the combination of a vesselhaving a top opening, a

screen mounted horizontally across the opening,-

aplurality of bars mounted in the walls of the opening to extend across the screen, thebars having sharp'edges engaging the screen from beneath, a capillary tube connected at one endto the vessel and mounted horizontally with its passage in the plane of the screen,` means for supplying the liquid to the vessel and tube, and means for pressing the sample flat upon the screen.

6. lApparatus Afor measuring the rate of absorption of a liquid by a sample of material, which comprises a vessel having a top opening, a screen mounted horizontally across the opening, a capillary tube connected at one end to the vessel and mounted horizontally with its passage in the plane of the screen, means for supplying the liquid tothe vessel and tube, a timing device, a l:carriage movable along the tube, means for pressing the sample upon the screen and simultaneously starting the timing device, means on the carriage for bearing a beam of light through the liquid column in the tube, and means for stopping the timing device, when the end of the liquid column has passed beyond the beam, said means including an element on the carriage intercept'ng the'. beam:` after it has passed' through the tube.

7S. Apparatus for measuring the: rate of absorption oi a liquid by a samplev of material, which comprises a vessel having atop opening, a screen mounted horizontally across the opening, a capillary tube` connected at. one end. to the vessel, a support for holding the tube horizontal with its passage in the plane: oi the screen, means for supplying the liquid to the vessel and tube, a timing device, a carriage mounted on the support and movable along the tube, means for pressing the sample upon the, screen and simultaneously starting the timing device, means on the carriage; for passing a beam of light through the liquid column in the tube, and means for stopping the timing device, when the end. of. the liquid column has passed beyond the beam, said means including an element on. the carriage; in-V tercepting the beam afterit hasl passed through the tube.

S. In apparatus for measuring the rate or" absorption oi a liquid by a sample oi' material, the combina-tion of a vessel having a top opening, a screen mounted across the opening, a plate overlying the screen and having a central opening through which part oi the screen isV exposed, a tubular member extending upwardly from the plate around and spaced from said central opening, said member being adapted to support a sample spaced above the screen, means for supplying liquid to the vessel and maintaining the level of the liquid in the planeU of the screen, and' means operable to engage the upper surface of a sample resting on the tubular member and press the sample downwardly into face contact with the screen.

9. In apparatus for measuring the rate of absorption oi a liquid by a sample of material, the combination oi a vessel having a top opening, a screen mounted across the opening, a tubular member extending upwardly around the screen and adapted to support a sample spaced above the screen, means for supplying liquid to the vessel and maintaining the level of the liquid in the plane of the screen, and means operable to engage the upper surfacev of a sample resting on the tubular memberl and press the sample downwardly into facev contact with the screen.

10. In apparatus for measuring the rate of ab sorption of a liquid by a sample oi material, the combination of a vessel having a top opening, a screen mounted across the opening, a tubular member extending upwardly around the screen and adapted to support a sample spaced above the screen, means for supplying liquid to the vessell and maintaining the level of the liquid in the plane of the screen, a plate` adapted to engagel the upper surface of a sample resting on the tubular member and press `the sample' into face contact with the screen, and' a mounting movably supporting the plate.

ll. In apparatus for measuring the rate of absorption of a liquid by a sample of material', the combination of a vessel having a top opening', a screen mounted across the opening, a tubular member extending upwardlyy around the screenand adapted to; support a. sample: spaced above the.` screen, means fer.z supplyingv liquid to the vessel andv maintaining the level of the liquid in the. plane of. the screen, a plate adapted to engage the upper surface of a sample. resting. on the tubular: member and press the sample into face. contact. with the screen, an arm mounted to swingto.- bring a portion thereof. over the screen, and a sternA attached to the plate and movably carriedl by said portion of thev arm.

l2. Apparatus4 for' measuring the rate of absorptionv of a liquid. by a sample. of material, whichY comprises a vessel. having a top open-ing, a flat liquid-permeable support mounted horizontally across the opening, the support having openings through which liquid may pass without appreciable resistancerto a iiow, a capillary tube4 connected atone end. to the vessel and mounted horizontally with its passage substantially in the plane of the support, means for supplying liquid to the vessel and tube, a timing device, means forl pressing the sample upon the support and simultaneously starting the timing device, and means operable, when the end of the liquid column in the tube passes a selected point, for stopping the timing device;

13. I-n apparatus for measuring the rate of absorption of' a liquid by a sample of' material, the combination of avessel having a top opening, a screen mounted across the topA opening, means surrounding the screen and extending upwardly above the level of the screen for supporting a sample above the screen, means for maintaining the level of the liquid in the. vessel in the. plane of the screen, and means operable.' to engage the top surfaceV of a sample resting on said support.- ing means and press. the sample into: contact with they screen.

141. In apparatus for measuring therate oi absorption of a liquid by a sample oi material, the combinationof al vessel having a top. opening, a screen mounted across the top opening', means surrounding the screen andextending upwardly above the Ievel'- of the screen for supporting a sampleabovethe screen, means for maintaining the level of the liquidi inthe vessel in the plane of the screen; a plate overlying the screen and having an opening through which the screen is exposed, arl-da movabl'y mounted element operablev to engage thel upper surface of. a. sample resting upon the supporting means and press the sample iin-to contact with the screen throughout the exposed area thereof andi with the surface of the plate around' the open-ing therein.

STANLEY PAUL I-IUllIT';l

REFERENCES CITED The following references are of record in the le of this patent?. .Y

UNITED STATES PATENTS Number Name Date 1,525,495 Carson Feb. 10,1925 1,708,074 Allen Apr. 9, 1929 2,329,959r Van Den Akker Sept. 21, 1943 

